Digital clock

ABSTRACT

A digital clock wherein minutes, tens of minutes, and hours display indicators are rotated by a motor in order to bring successive numerals into position behind a viewing window 82. Geneva gears 113 and 115 are grouped at the left of the numerals for driving an hours drum 56 and a tens of minutes numeral drum 58, and the drums are uniquely supported with respect to each other so that they may be driven by a motor 8 which is located at the right of the numerals.

[4 1 July 16,1974

United States Patent [191 Boyles 58/125 C X 58/125 C X 58/125 C 58/125 CX 133 5557 9999 1111 HMWW 1 l wwmw 2 2 66ll 735 2223 m d, v m n 1. a Wn. m W 0 9C 8 n. n o m B I E 1 K n m C, e 8 0 b n L o e C R.G n aw t. nn m .m m m m D I A l. 4 5 3 5 7 7 .1 r1 .1

Bridgeport, Conn.

Mar. 8, 1973 Primary ExaminerRichard B. Wilkinson Assistant Examiner-VitW. Miska [22] Filed:

Attorney, Agent, or Firm-L. J. Platt; G. R. Powers; .1. F. Cullen 21Appl. No.: 339,213

ABSTRACT A digital clock wherein minutes, tens of minutes, and hoursdisplay indicators are rotated by a motor in order to bring successivenumerals into position behind a viewing window 82. Geneva gears 113 and115 are grouped at the left of the numerals for driving an hours drum 56and a tens of minutes numeral drum 58, and the drums are uniquelysupported with respect to each other so that they may be driven by amotor 8 which is located at the right of the numerals.

References Cited UNITED STATES PATENTS 10 Claims, 12 Drawing Figures CA5 2 13 l 8/ 55 3 2 2,130,873 Boyrquin...........................2,191,616 2/1940 Grizey..... 2,351,814 6/1944 Ho1zwer......

ATENTEU JUL 1 51974 SHEEI EUF 4 DIGITAL CLOCK BACKGROUND OF THEINVENTION 1. Field of the Invention This invention relates to a digitalclock, and more particularly to a mechanism for supporting and indexinghours, tens of minutes, and minutes numerals of such a digital clock.

In devices of this type it has been common practice to provide hours,tens of minutes, and minutes numerals on drums or wheels which arerotated by an electric motor in order to bring successive numerals intoposition behind a viewing window. It is desirable that the indexing ofthe rotatable drums or wheels from one numeral to a next succeedingnumeral occur rapidly so that one numeral may be viewed for a relativelylong period of time, and then, the next succeeding numeral may bequickly advanced into position where it may be viewed for a relativelylong period of time.

2. Description of the Prior Art The prior art includes many differentconstructions and arrangements for quickly moving clock numerals andother numerals from one position toa next succeeding position. Genevagears are frequently employed, and for example, in one prior artconstruction as shown in U.S. Pat. No. 2,483,359 to Bliss dated Sept.27, 1949, a geneva mechanism is located below and between clock numeraldrums for indexing the numeral drums from one position to a nextsucceeding position.

In another prior art construction as shown in a patent to Holzner, U.S.Pat. No. 2,636,339 dated Apr. 28, 1953, an indexing gear mechanism islocated inside of a numeral drum for moving the drum from one positionto another position.

This invention is concerned with such drive mechanisms for digitalclocks and timers, and more particularly, to a gear and drivingarrangement which is uniquely constructed so that the numeral drums maybe positioned relatively close to each other in order to minimize,unsightly spaces between the drums. It is also desirable to provide aninexpensive driving arrangement for such a digital clock.

Accordingly, it is a primary object of my invention to provide animproved digital clock having a simplified drive mechanism havingrelatively few parts which may be readily manufactured and assembled toeach other.

It is a further object of my invention to provide an improved digitalclock wherein the driven mechanism may be located to the right and leftof the numerals to minimize unsightly spaces between the numerals and toprovide a compact low profile digital clock.

SUMMARY OF THE INVENTION In accordance with one of the aspects of thisinvention a digital clock includes a rotatable minutes drum having anelongated shaft fixed thereto. A rotatable tens of minutes drum is alsoprovided with a relatively long shaft and is mounted on the shaft of theminutes drum in coaxial arrangement therewith. A geneva wheel is fixedto an end portion of the tens of minutes shaft for driving the tens ofminutes shaft and the tens of minutes drum which is fixed thereto. Atens of minutes geneva driver cam is positioned adjacent to the tens ofminutes geneva wheel and is arranged for meshing engagement with thetens of minutes geneva wheel. A gear having conventional gear teeth isintegrally formed with the tens of minutes geneva driver cam, andanother gear having conventional gear teeth is fixed to the minutesshaft. The conventional gear of the minutes shaft is arranged in meshingengagement with the conventional gear which is integrally formed withthe tens of minutes geneva driver cam. With this unique simplifiedconstruction, the tens of minutes geneva driver carn'and the tens ofminutes geneva wheel may be compactly located in a limited amount ofspace and may be readily driven by the minutes shaft.

This construction also permits the minutes drum and the tens of minutesdrum to be positioned relatively close to each other in order tominimize unsightly spaces between the drums. Both the minutes shaft andthe tens of minutes shaft are elongated so that the geneva wheel, thegeneva driver and the two conventional 7 gears may all be positionedsubstantially to one side of not only the minutes drum and the tens ofminutes drum but also an hours drum. Thus, a minutes, tens of minutes,and hours drum may be readily mounted and positioned within a digitalclock relatively close to each other without unsightly spaces betweenthe drums.

The drive mechanism for the tens of minutes drum is also quite simpleand has relatively few parts which may be readily manufactured andassembled to each other. The tens of minutes geneva wheel may be readilyfixed to an end portion of the elongated tens of minutes shaft while theconventional gear which is fixed to the minutes shaft may be positionedimmediately adjacent to and coaxial with the tens of minutes genevawheel. Moreover, the gearing between the minutes shaft and the tens ofminutes geneva driver may include a conventional gear which isintegrally formed with the geneva driver cam. The gears, geneva wheelsand geneva drivers are positioned relatively close to each other, andthus, a very compact, exceedingly simple, reliable, and readilymanufactured digital clock has been achieved.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects and attendant advantagesof the invention will be apparent from the following description takenin connection with the accompanying drawing in which;

FIG. I is a front perspective view of a digital clock constructedin'accordance with my invention;

FIG. 2 is a front perspective view generally similar to FIG. I with theouter casing removed for purposes of illustration;

FIG. 3 is a fragmentary exploded front perspective view of the clockillustrated in FIGS. 1 and 2;

FIG. 4 is a front elevational view of the clock shown in FIG. 2;

FIG. 5 is a cross-sectional view of the clock taken substantially on theplane of 55 of FIG. 4;

FIG. 6 is a cross-sectional view of the digital clock takensubstantially on the plane of 6-6 of FIG. 4 show ing one of the numeralpages being flipped to display a numeral on the other side of the page;

FIG. 7 is a crosssectional view of the clock also taken on the plane of6-6 of FIG. 4 showing the numeral pages in a difi'erent operatingposition;

FIG. 8 is a cross-sectional view of the clock taken substantially on theplane of 8-8 of FIG. 4;

FIG. 9 is a cross-sectional view of the clock taken substantially on theplane 99 of FIG. 4 showing the details of construction of a drive fingerand detent lever arrangement for advancing a minutes drum from oneposition to a next succeeding position and for holding the minutes drumin an accurate viewing position, the parts being shown with the detentlever holding the ratchet wheel of the minutes indicator member in anaccurate viewing position;

FIG. 10 is a cross-sectional view of the digital clock also takensubstantially on the plane of 99 of FIG. 4 showing the drive fingerarrangement with the finger holding the detent lever away from theratchet wheel while the finger moves the ratchet wheel from one positionto a next succeeding position;

FIG. 11 is a cross-sectional view of the digital clock also takensubstantially on the plane of 9-9 of FIG. 4 showing the finger graduallylowering the detent lever onto one of the teeth of the ratchet wheel;and

FIG. 12 is an enlarged partial cross-sectional view of the tens ofminutes and hours geneva mechanism taken substantially on the plane 5-5of FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing,and first particularly to FIGS. 1 and 2, there is shown a digital clockwhich includes my unique and simplified mechanism for supportingminutes, tens of minutes, and hours display indicators, and a uniquemechanism for driving the tens of minutes and hours display indicators.As shown, the digital clock numerals may conveniently include three setsof pages 2, 4 and 6 for indicating minutes, tens of minutes, and hours,respectively.

The digital clock may be driven by a conventional self-startingsynchronous motor 8 having a magnetic core 10 and energizing coil 12. Asshown in FIG. 2, the motor may be readily attached to an end plate 14 ofthe clock by means of screws 16 and 18 or other suitable securing means,and as shown in FIG. 5, an output shaft 20 of the motor extends throughan aperture 22 which is formed in the end plate 14.

As shown more particularly in FIGS. 2, 5, 6 and 7, the minutes numerals2 are printed or otherwise formed on both sides of five pages 24, 26,28, 30 and 32, and the pages are pivotally mounted on flanges 34 and 36of a rotatable minutes drum 38.

A generally similar arrangement is used for the hours display indicator6. l2 numerals are required for the hours display, and this isaccomplished by using six panels 40, 42, 44, 46, 48 and 50, which arepivotally mounted on flanges 52 and 54 of a rotatable hours drum 56.

A tens of minutes display indicator 4 requires six digits, and thus, thetens of minutes numerals may be made the same size as the hours andminutes numerals without the use of flippable pages that have numeralson both sides of the pages. As shown more particularly in FIGS. 3 and 5,the tens of minutes numerals are conveniently positioned on the outersurface of a six sided tens of minutes drum 58.

HOURS, MINUTES, & TENS OF MINUTES SUPPORTING CONSTRUCTION In accordancewith my invention the minutes, tens of minutes, and hours drums areuniquely and inexpensively supported for rotation between mountingplates 60 and 62. A minutes spool drum 38 is fixed to a centrallypositioned shaft 64 by means of knurling 66 or other suitable connectingmeans. As shown, the shaft 64 extends a considerable distance to theleft of the spool and is supported for rotation within a bearing 61which is formed in a stub shaft 63 which is fixed to a plate 112.

The right end portion of the minutes shaft 64 is formed with a bearingsurface 74 which is supported within a bearing 76 which is integrallyformed with end plate 60. As shown more particularly in FIGS. 3 and 5,the supporting plate 60 may be formed of plastic or other suitablematerial, and it includes an outwardly extending portion 80 forintegrally connecting the bearing portion 76 with the main portion ofthe supporting plate.

The tens of minutes drum 58 is fixed to a hollow support shaft 68 whichis mounted for rotation on the minutes shaft 64, and the hours drum 56is supported for rotation on the hollow shaft 68 of the tens of minutesdrum 58.

The minutes drum 38 is quickly indexed from one numeral position to anext succeeding numeral position in about five seconds of time, and itis held in appropriate positions to display numerals midway between theupper and lower edges of a viewing window 82, illustrated in FIG. 1. Asshown more particularly in FIGS. 3 and 5, a ratchet wheel 84 having fiveteeth may be integrally formed with the minutes drum 38 forincrementally driving the minutes drum and the shaft 64 which is fixedto it.

A drive finger 96 is eccentrically mounted for rota tion with respect tothe ratchet wheel 84 to engage and move one tooth of the ratchet wheelfor each revolution of the drive finger 96. As shown more particularlyin FIGS. 3 and 5, the drive finger 96 may be integrally formed on areduction gear unit 98 which is positioned between the output shaft 20of the electric motor 8 and the ratchet wheel 84. The reduction gearunit 98 is supported between plates 60 and 104 on a shaft 100 which isintegrally formed with the reduction gear unit. As shown in FIG. 5, theshaft 100 is mounted for rotation within apertures 102 and 103 which areprovided in mounting plates 60 and 104, respectively.

The apertures 102 and 103 are located somewhat rearwardly of the axis ofthe ratchet wheel 84 in order to provide the desired eccentricitybetween the ratchet teeth 86, 88, 90, 92 and 94, and the drive finger96. With this construction, the output pinion 20 of the motor drives agear 106 of the integrally formed reduction gear unit 98 to move thedrive finger 96 at one revolution per minute. With reference to FIG. 3,it can be appreciated that the drive finger 96 will remain in engagementwith a tooth of the ratchet wheel 84 for about 30 of travel of thereduction gear unit, and accordingly, movement of the minutes drum 38from one position to a next succeeding position will occur in therelatively short span of about 5 seconds. A spring loaded detent lever108 is provided for holding the ratchet wheel 84 in any one of aplurality of numeral positions.

The details of the unique construction for holding the minutes numeraldrum 38 in an appropriate position behind the viewing window 82 and forquickly advancing the minutes numeral drum 38 from one position to anext succeeding position does not form a part of this invention, and isdescribed and illustrated in greater detail in my co-pending applicationSer. No. 339,414, assigned to the same assignee as the presentinvention.

TENS OF MINUTES & HOURS INDEXING MECHANISM In accordance with myinvention, the tens of minutes drum 58 and the hours drum 56 are quicklyindexed from one numeral position to a next succeeding numeral positionby a geneva mechanism 110. As shown in FIGS. 3 and 5, the genevamechanism 111) is located at the left of the numerals and is readilysupported and positioned on the digital clock without substantiallyincreasing the overall size of the clock. A mounting plate 112 isarranged generally parallel to mounting plate 62 for supporting a pairof geneva driver cams 114 and 116 therebetween. As shown moreparticularly in FIG. 12, the geneva driver cams 114 and 116 are coaxialwith each other and are supported on a common shaft 117. The genevadriver cam 116 is integrally formed to include a pair of driving fingers120 and 122, a toothed gear 124, a hollow shaft portion 126, and apinion gear portion 128 at the left portion of shaft 126. Geneva drivercam 114 is integrally formed to include a driving finger 130, a toothedgear 134, and a generally circular sleeve bearing 136 which is supportedfor rotation on the coaxial shaft 126 of the integrally formed genevadriver cam 116. The shaft 126 is fonned to include a central hollowcylindrical bearing surface 136 for receiving shaft 117. Thus, as shownin FIG. 12, the supporting shaft 117 may be positioned within apertures119 and 121 which are formed in plates 119 and 62, respectively, andreadily held between the plates for supporting the geneva driver cams114 and 116.

The geneva driver cam 114 is arranged for driving a tens of minutesgeneva wheel 115 while the geneva driver cam 116 is arranged for drivingan hours geneva wheel 113. As shown more particularly in FIG. 5, thegeneva wheel 113 is integrally formed with the hours drum 56 forindexing the hours drum one increment every hour, and the generallysimilar geneva wheel 115 is fixed to the hollow shaft 68 of the tens ofminutes drum 58 for indexing the tens of minutes drum one incrementevery tenminutes. The pair of geneva driver cams 114 and 116 arepositioned behind the geneva wheels 113 and 115, respectively, fordriving the geneva wheels, and thus, the geneva wheels and the genevadrivers form a compact arrangement which does not increase the overallheight of the clock.

With particular reference to FIG. 5, it can be seen that a gear 140 isfixed to the minutes shaft 64 for driving the geneva mechanism 110 toadvance the hours drum 56 one increment every hour and to advance thetens of minutes drum 58 one increment every minutes. Gear 140 isarranged in mesh with gear 134 of the tens of minutes geneva driver cam114, and with one driving finger 130 on the geneva driver cam 114, thegearing ratio between gears 140 and 134 will enable the timing motor 8to rotate the geneva driver cam 114 once every l0 minutes. Thus, every10 minutes the geneva driver finger 130 will be moved into one of thenotches on the geneva wheel 115 to rotate the tens of minutes genevawheel 115 one increment every 10 minutes.

As shown more particularly in FIG. 3, a gear 144 is integrally formedwith the tens of minutes geneva wheel 115 for driving the hours genevadriver cam 124. Gear 144 is arranged in mesh with gear 124 and with twodriving fingers and 122 on the hours geneva driver cam 116 the gearratio between gear 144 and gear 124 of the hours geneva driver cam isarranged so that the hours geneva driver cam makes one revolution every2 hours. Accordingly, one of the driving fingers 120 or 122 is movedinto one of the notches of the geneva gear 113 once every hour to movethe hours drum 56 once every hour.

In operation, it can be appreciated that the minutes drum 38 rotatesshaft 64 and gear at two revolutions every 10 minutes. Gear 140 isarranged in mesh with gear 134 which is integrally formed with the tensof minutes geneva driver cam 114, and thus, the tens of minutes genevadriver cam 114 drives the tens of minutes geneva wheel 115 and the tensof minutes drum 144 at one increment every 10 minutes and one revolutionper hour. The gear 144 which is integrally formed with the tens ofminutes geneva wheel 115 is in mesh with the gear 124 of the hoursgeneva driver cam, and thus, the hours geneva driver cam 116 is rotatedto move the hours geneva wheel 113 one increment every hour.

From the foregoing description it can be appreciated that my uniquesupporting and driving construction for a drum-type digital clock isachieved with the use of relatively few parts which may be readilyassembled in the clock. The geneva driver cams 114 and 116 are coaxiallymounted with respect to each other to include a common supporting shaft117 and integrally formed toothed gears 124 and 134 which are arrangedin mesh with gears 140 and 144 for inexpensively driving the genevamechanism. In like manner, the geneva wheels 113 and 115 are readilyfonned and coaxially positioned with respect to each other. Geneva wheel113 is integrally formed with the hours drum 56, while the tens ofminutes geneva wheel 115 is integrally formed with a gear 144 fordriving the hours geneva driver cam 116. Thus, a very compact genevadriving mechanism at the left side of the numerals is achieved. Withsuch a construction, no driving mechanisms are positioned between thenumeral drums and the drums may be located relatively close to eachother without having unsightly large spaces between the drums. Inaddition, it can be seen that with the geneva mechanism 110 located tothe left and rear of the numerals, and the motor 8 located to the rightof the numerals, a compact low profile digital clock is constructed.

TIME SET A mechanism for rotating the minutes, tens of minutes, andhours drums 38, 58 and 56, respectively, to set the hours, minutes andtens of minutes numerals may be readily incorporated with the digitalclock mechanism thus far described. As shown more particularly in FIG.5, a time set gear 146 may be positioned in mesh with gear 140. Asshown, gear 146 is supported on a shaft 148 which may be convenientlyfixed to mounting plate 62. A portion of gear 146 may extend through thecasing of the clock, as shown in FIG. 1, and it can be appreciated thatrotation of gear 146 will cause corresponding rotation of gear 140 whichin turn will cause rotation of the minutes drum 38 through shaft 64, andthe hours and tens of minutes drums 56 and 58, respectively, through thegeneva gear mechanism 110, in order to set the time.

ALARM MECHANISM In acqordance with my invention, the geneva drivingmechanism 114 is also uniquely designed so that it may readily drive analarm mechanism 160. With particular reference to FIG. 3, it can beappreciated that the hours geneva driver cam 1 16 is driven at sixrevolutions every 12 hours, and thus, it may be readily utilized fordriving a 12 hour cam gear 162 of a 12 hour alarm mechanism. To achievethis, the hours geneva driver cam 116 is fixed to an elongated shaft 126which extends through the tens of minutes geneva driver cam 114, and aconventional gear 128 is integrally formed on the left end portion ofshaft 126. As shown in FIG. 5, gear 128 is arranged in mesh with the 12hour cam gear 162 to drive the cam gear 162 at one revolution every 12hours.

Conventional 12 hour alarm cam mechanisms include two coaxially mountedgears which are provided with interacting cams for causing relativeaxial movement of the gears at a present alarm time for actuating aswitch or other alarm mechanism. Thus, as shown in FIG. 5, the cam gear162 may be formed with two leftwardly extending projections 163 and 165for cooperating with slots 164 and 166 which may be formed in a manuallyadjustable alarm set cam 168.

In view of the foregoing, it can be appreciated that my geneva drivingmechanism 110 is uniquely constructed so that it may readily drive analarm mechanism without the use of additional parts. Thegear 128 fordriving the alarm mechanism is integrally formed with the hours genevadriver shaft 126 at the same time that the drivefingers 120 and 122 andthe other portions of the hours geneva driver cam are being formed.Thus, an exceedingly simple and reliable mechanism is achieved with theuse of relatively few parts which may be readily connected to eachother.

What I claim is:

l. A digital clock comprising:

a. a rotatable minutes drum having an elongated shaft fixed thereto;

b. a rotatable tens of minutes drum having a shaft fixed thereto, saidtens of minutes drum and said tens of minutes shaft being coaxial withand mounted for rotation on said minutes shaft;

0. a geneva wheel fixed to said tens of minutes shaft for driving saidtens of minutes drum;

d. an integrally formed gear and tens of minutes geneva driver campositioned outwardly from said minutes drum and said tens of minutesdrum for driving said tens of minutes drum, said tens of minutes genevadriver cam mounted for meshing engagement with said tens of minutesgeneva wheel; and

e. a gear positioned outwardly from said minutes drum and said tens ofminutes drum coaxial with and fixed to said minutes shaft in meshingengagement with the gear integrally formed with said tens of minutesgeneva driver cam for driving said tens of minutes geneva driver cam andsaid tens of minutes geneva wheel.

2. A digital clock as defined in claim 1 wherein an hours drum ismounted for rotation on said tens of minutes shaft between said tens ofminutes drum and said tens of minutes geneva wheel.

3. A digital clock comprising:

a. a rotatable minutes drum having a shaft fixed thereto;

b. a rotatable tens of minutes drum having a shaft fixed thereto, saidtens of minutes drum and said tens of minutes shaft being mounted forrotation on said minutes shaft;

c. an hours drum mounted for rotation on said tens of minutes shaft;

d. a geneva wheel integrally formed with said hours drum for drivingsaid hours drum;

e. a geneva wheel fixed to said tens of minutes shaft for driving saidtens of minutes drum;

f. an hours geneva driver cam mounted for meshing engagement with saidhours geneva wheel;

g. a tens of minutes geneva driver cammounted for meshing engagementwith said tens of minutes geneva wheel, said tens of minutes genevadriver cam having a gear integrally formed therewith;

h. a gear fixed to said minutes shaft in meshing engagement with thegear integrally formed with said tens of minutes geneva driver cam fordriving said tens of minutes geneva driver cam and said tens of minutesgeneva wheel; and

i. a toothed gear'integrally formed with said tens of minutes genevagear in meshing engagement with a toothed gear integrally formed withsaid hours geneva driver cam for driving said hours geneva driver camand said hours geneva wheel.

4. A digital clock as defined in claim 3 wherein said geneva driver camsare coaxially mounted with respec to each other.

5. A digital clock as defined in claim 4 wherein said geneva driver camsare located between two supporting plates, a shaft is fixed between saidsupporting plates, and both of said geneva driver cams are coaxiallymounted on said shaft.

6. A digital clock as defined in claim 3 wherein a gear is arranged inmeshing engagement with the gear on said minutes shaft for setting theminutes, hours, and tens of minutes drums.

7. A digital clock as defined in claim 3 wherein said tens of minutesand hours geneva wheels are approximately the same size as each otherand are coaxially mounted with respect to each other.

8. A digital clock as defined in claim 3 wherein said geneva driver camsare approximately the same size as each other and said hours genevadriver cam has two drive fingers while the tens of minutes driver camhas one drive finger.

9. A digital clock as defined in claim 3 wherein the hours geneva drivercam is integrally formed with an elongated shaft which extends throughthe tens of minutes geneva driver cam, and an end portion of saidelongated shaft includes an integrally formed conventional gear which isarranged in mesh with a conventional gear of an alarm cam mechanism.

10. A digital clock comprising:

a. three support plates arranged generally parallel to and spaced fromeach other, the two outer support plates being provided with hearingmembers and the inner support plate being positioned between the twoouter support plates;

b. a rotatable minutes drum having an elongated shaft fixed thereto,said shaft having two end portions;

c. one of the end portions of said minutes shaft being mounted forrotation in the bearing member of one of said outer support plates andthe other end portion of said shaft being mounted in the other hearingmember in the other outer support plate;

d. a rotatable tens of minutes drum having an elongated shaft fixedthereto, said tens of minutes drum and said tens of minutes shaft beingmounted for rotation on said minutes shaft;

e. an hours drum mounted for rotation on said tens of minutes shaft,said tens of minutes shaft and said minutes shaft extending coaxiallythrough a central bearing portion of said hours drum;

f. a geneva wheel integrally formed with said hours drum for drivingsaid hours drum; and

g. a geneva wheel fixed to said tens of minutes shaft for driving saidtens of minutes drum;

h. an integrally formed gear and tens of minutes geneva driver campositioned outwardly from said minutes drum and said tens of minutesdrum for driving said tens of minutes drum, said tens of minutes genevadriver cam mounted for meshing engagement with said tens of minutesgeneva wheel; and

i. a gear positioned outwardly from said minutes drum and said tens ofminutes drum coaxial with and fixed to said minutes shaft in meshingengagement with the gear integrally formed with said tens of minutesgeneva driver cam for driving said tens of minutes geneva driver cam andsaid tens of minutes geneva wheel.

1. A digital clock comprising: a. a rotatable minutes drum having anelongated shaft fixed thereto; b. a rotatable tens of minutes drumhaving a shaft fixed thereto, said tens of minutes drum and said tens ofminutes shaft being coaxial with and mounted for rotation on saidminutes shaft; c. a geneva wheel fixed to said tens of minutes shaft fordriving said tens of minutes drum; d. an integrally formed gear and tensof minutes geneva driver cam positioned outwardly from said minutes drumand said tens of minutes drum for driving said tens of minutes drum,said tens of minutes geneva driver cam mounted for meshing engagementwith said tens of minutes geneva wheel; and e. a gear positionedoutwardly from said minutes drum and said tens of minutes drum coaxialwith and fixed to said minutes shaft in meshing engagement with the gearintegrally formed with said tens of minutes geneva driver cam fordriving said tens of minutes geneva driver cam and said tens of minutesgeneva wheel.
 2. A digital clock as defined in claim 1 wherein an hoursdrum is mounted for rotation on said tEns of minutes shaft between saidtens of minutes drum and said tens of minutes geneva wheel.
 3. A digitalclock comprising: a. a rotatable minutes drum having a shaft fixedthereto; b. a rotatable tens of minutes drum having a shaft fixedthereto, said tens of minutes drum and said tens of minutes shaft beingmounted for rotation on said minutes shaft; c. an hours drum mounted forrotation on said tens of minutes shaft; d. a geneva wheel integrallyformed with said hours drum for driving said hours drum; e. a genevawheel fixed to said tens of minutes shaft for driving said tens ofminutes drum; f. an hours geneva driver cam mounted for meshingengagement with said hours geneva wheel; g. a tens of minutes genevadriver cam mounted for meshing engagement with said tens of minutesgeneva wheel, said tens of minutes geneva driver cam having a gearintegrally formed therewith; h. a gear fixed to said minutes shaft inmeshing engagement with the gear integrally formed with said tens ofminutes geneva driver cam for driving said tens of minutes geneva drivercam and said tens of minutes geneva wheel; and i. a toothed gearintegrally formed with said tens of minutes geneva gear in meshingengagement with a toothed gear integrally formed with said hours genevadriver cam for driving said hours geneva driver cam and said hoursgeneva wheel.
 4. A digital clock as defined in claim 3 wherein saidgeneva driver cams are coaxially mounted with respect to each other. 5.A digital clock as defined in claim 4 wherein said geneva driver camsare located between two supporting plates, a shaft is fixed between saidsupporting plates, and both of said geneva driver cams are coaxiallymounted on said shaft.
 6. A digital clock as defined in claim 3 whereina gear is arranged in meshing engagement with the gear on said minutesshaft for setting the minutes, hours, and tens of minutes drums.
 7. Adigital clock as defined in claim 3 wherein said tens of minutes andhours geneva wheels are approximately the same size as each other andare coaxially mounted with respect to each other.
 8. A digital clock asdefined in claim 3 wherein said geneva driver cams are approximately thesame size as each other and said hours geneva driver cam has two drivefingers while the tens of minutes driver cam has one drive finger.
 9. Adigital clock as defined in claim 3 wherein the hours geneva driver camis integrally formed with an elongated shaft which extends through thetens of minutes geneva driver cam, and an end portion of said elongatedshaft includes an integrally formed conventional gear which is arrangedin mesh with a conventional gear of an alarm cam mechanism.
 10. Adigital clock comprising: a. three support plates arranged generallyparallel to and spaced from each other, the two outer support platesbeing provided with bearing members and the inner support plate beingpositioned between the two outer support plates; b. a rotatable minutesdrum having an elongated shaft fixed thereto, said shaft having two endportions; c. one of the end portions of said minutes shaft being mountedfor rotation in the bearing member of one of said outer support platesand the other end portion of said shaft being mounted in the otherbearing member in the other outer support plate; d. a rotatable tens ofminutes drum having an elongated shaft fixed thereto, said tens ofminutes drum and said tens of minutes shaft being mounted for rotationon said minutes shaft; e. an hours drum mounted for rotation on saidtens of minutes shaft, said tens of minutes shaft and said minutes shaftextending coaxially through a central bearing portion of said hoursdrum; f. a geneva wheel integrally formed with said hours drum fordriving said hours drum; and g. a geneva wheel fixed to said tens ofminutes shaft for driving said tens of minutes drum; h. an integrallyformed gear and tens of minutes geneva driver cam positioned outwArdlyfrom said minutes drum and said tens of minutes drum for driving saidtens of minutes drum, said tens of minutes geneva driver cam mounted formeshing engagement with said tens of minutes geneva wheel; and i. a gearpositioned outwardly from said minutes drum and said tens of minutesdrum coaxial with and fixed to said minutes shaft in meshing engagementwith the gear integrally formed with said tens of minutes geneva drivercam for driving said tens of minutes geneva driver cam and said tens ofminutes geneva wheel.